A mixed-space approach to first-principles calculations of phonon frequencies for polar materials.

We propose a mixed-space approach using the accurate force constants calculated by the direct approach in real space and the dipole-dipole interactions calculated by linear response theory in reciprocal space, making the accurate prediction of phonon frequencies for polar materials possible using the direct approach as well as linear response theory. As examples, by using the present approach, we predict the first-principles phonon properties of the polar materials α-Al(2)O(3), MgO, c-SiC, and h-BN, which are in excellent agreement with available experimental data.

[Heat transfer analysis of liquid cooling garment used for extravehicular activity].

Brief description was given about the construction and function of the LCG (liquid cooling garment) used for EVA (extravehicular activity). The heat convection was analyzed between ventilating gas and LCG, the heat and mass transfer process was analyzed too, then a heat and mass transfer mathematical model of LCG was developed. Thermal physiological experimental study with human body wearing LVCG (liquid cooling and ventilation garment) used for EVA was carried out to verify this mathematical model. This study provided a basis for the design of liquid-cooling and ventilation system for the space suit.

Blood selenium levels in nasopharyngeal cancer patients in south China.

Blood selenium concentrations in 111 nasopharyngeal cancer patients and 56 normal subjects were determined using a modified 2,3-diamino naphthalene fluorometric method. Cancer subjects in this study were divided into two groups and blood Se levels (mean +/- SD) were 0.105 +/- 0.024 for untreated cases, 0.113 +/- 0.034 for those who had received treatment, and 0.109 +/- 0.030 microgram/ml for all subjects. The results suggest that low blood Se levels in nasopharyngeal cancer patients are a consequence of their disease rather than the cause of the cancer.